Help needed

One is from complex numbers. I'm in XIth, need help, i have the formulas, but i can't solve it ,unfortunately. Someone explain it, or atleast solve it please.
And if anyone can give related questions for me to practise, i don't mind.
Thanks in advance. I've been trying it the whole day, and my its doing my head in.

Re: Help needed

For the first one, use the trig identity for tan(A+B) and notice that 95+4.
For the second one, the general advice is that to raise a complex number to some power, first switch to polars.
For the third one make use of the identity for cosA + cosB.